1. Field of the Invention
This invention relates to a mining machine, and more particularly, to a mining machine having a dust collecting system that includes a pair of ducts each extending longitudinally on each side of the frame of the mining machine and are connected by a crossover duct assembly with a plurality of pivotal gates positioned in the longitudinal and crossover ducts to control the flow of air through the duct system to and from the mine face.
2. Description of the Prior Art
In underground mining, it is well known to provide a continuous mining machine which includes a material dislodging mechanism positioned on the front end of the mining machine for dislodging material from a mine face. The dislodged material is conveyed rearwardly of the mining machine by a conveying system positioned on the mining machine. The mining machine continuously advances and dislodges the material being mined to form an entry in the material seam.
Duct assemblies on mining machines are known, such as disclosed in U.S. Pat. No. 3,712,678 directed to a dust collecting system carried on a boom of the mining machine.
Contrarotary centrifugal fans collect dust entrained air which is conveyed through ductwork extending on either a side of the body of the mining machine. A scrubber may also be associated with the ductwork.
U.S. Pat. No. 3,792,568 discloses a scrubber for use on a continuous mining machine utilizing a rotor, a wetting agent and baffles. The cleaned air is directed back toward the mine face and the wetted particulates are discharged onto the conveyor of the mining machine.
U.S. Pat. No. 3,810,677 discloses a scrubber device for use on an underground mining machine utilizing air intakes adjacent to the mining machine cutting heads, a wetting agent, and a centrifugal fan mounted between rotor plates that project air and dust particles against a spiral outer wall of the rotor housing. This scrubber device is located on the boom of the mining machine. The resultant slurry is discharged onto the conveying means of the mining machine.
U.S. Pat. No. 4,076,315 discloses a dust abatement device for a mining machine utilizing a water spray and a centrifugal fan that draws dust entrained air into its center and impinges the air with the particulates against the wetted fan blades and baffles to suspend the particles in solution. The cleaned air and slurry are then directed to the mine face to wet the dust produced by the mining machine head.
U.S. Pat. No. 4,157,204 discloses a mine ventilation system for use with a mining machine in which a line curtain conducts dust entrained air away from the mining area. A panel mounted on the mining machine acts as an extension of the line curtain. Water nozzles mounted on the panel direct a flow of dust entrained air into the line curtain. Water spray nozzles are mounted on the side of the mining machine, oppositely of the line curtain. The machine mounted nozzles form a water barrier in the gap between the line curtain and the machine mounted panel.
U.S. Pat. No. 4,249,778 discloses method and apparatus for removing moisture from air after it has passed through a scrubber on a mining machine. A demister includes a sump that projects above the bottom wall of the demister at the outlet portion. The airflow through the demister moves upwardly creating a "dead" air space above the accumulated water level in the sump, thus preventing reentrainment of moisture.
U.S. Pat. No. 4,380,353 discloses a dust control device and a method of operation for use on a mining machine. The dust control device includes a vane axial fan comprising a housing having an inlet and an outlet with a motor mounted in the housing for rotating vanes of the fan. Upstream from the fan is a flooded bed scrubber having a plurality of layers of netted wire cloth of stainless steel wire having a preselected density for entrainment in droplets of water of dust. A demister is located between the fan and the scrubber, and a jet sump associated with the demister directs the water gathered to the top of the cutter head of the mining machine. A telescoping duct transition section is also disclosed.
U.S. Pat. No. 4,463,973 discloses a sealed hinge for use in an air duct system for connecting a suction source of the air duct with a inlet on a mining machine. The connection disclosed is a movable hinged section.
U.S. Pat. No. 4,531,784 discloses a dust collecting apparatus for use with a continuous mining machine that utilizes a high pressure fluid sprayed from manifolds to induce a flow of air through ductwork located between the boom arms of the mining machine and laterally of the boom arms on the mining machine. The dust collecting unit and the lateral units utilize a demister to separate the slurry produced from the cleaned air. The slurry is directed onto the conveyor of the continuous mining machine and the cleaned air is expelled adjacent the boom of the continuous mining machine.
U.S. Pat. No. 4,557,524 discloses on a mining machine a transitional ductwork for connecting the ductwork on a boom portion pivotally with the fixed ductwork on the frame of the mining machine. The transitional section consists of the end of the boom ductwork fitting into the fixed ductwork on the frame. The boom ductwork has top and bottom hinged plates to engage the inside of the top and bottom fixed ductwork walls. A sleeve-like outer piece fits over the junction of the boom and fixed ductworks to seal the sides of the ductwork.
U.S. Pat. No. 4,840,432 discloses a continuous mining machine having a hollow boom assembly pivotally attached to the frame of the mining machine. The hollow boom assembly has an inlet for receiving dust entrained air and is connected to ductwork in the mining machine frame. The ductwork on the mining machine frame includes a fan as a collecting means. The hollow boom assembly connects to the ductwork on the frame by forming arcuate ends which fit into and slidingly engage arcuate ends formed by the connecting portion of the ductwork on the mining machine frame.
U.S. Pat. No. 4,936,632 discloses a continuous mining machine having a hollow boom assembly acting as a duct for collecting dust entrained air pivotally attached to a mobile frame and ductwork connected to the hollow boom. The dust entrained air is collected in the hollow boom which is in fluid commmunication with the ductwork. The ductwork includes a first duct assembly extending longitudinally along one side of the continuous mining machine and connected to a fan assembly at the rear end of the continuous mining machine. The second duct assembly extends from the hollow boom to the side of the continuous mining machine opposite the first duct assembly and is located on and extends partially along that side of the continuous mining machine. The second duct assembly traverses the continuous mining machine between the conveyor reach and return reach.
While it is known to include various types of ductwork assemblies on continuous mining machines, the known devices do not disclose a dual duct assembly with each duct assembly having a reversible fan assembly. There is a need for an improved mining machine having a dual duct system with each duct system having a reversible fan assembly which allows the fan to act as a dust collector or as a mechanism for blowing air toward the mine face.
There is also a need for an improved mining machine having a dual duct system with the capacity to use either of two reversible fan assemblies to draw dust entrained air away from the mine face.